I was wondering about this myself, so I assembled a playlist to burn, about 12 minutes too long for a CD. And a dialog box popped up right then, telling me that this would require multiple CDs. I edited the playlist and burned away.
On the off-chance that I might use this CD for something, I had clicked both the CD Text and Sound Check options. What I did not anticipate is that iTunes would assume that I wanted Sound Check applied to all 7000-odd tracks, and would duly sit in the background counting decibels.
For six and a half hours.
It didn’t matter that I’d never checked the Sound Check box in Preferences; it didn’t matter that I shut down iTunes, let it back up its library a tedious process in itself and restarted it. Apple, by gum, wanted all those volume levels normalized, and it was going to happen. (It even survived a system power-off and reboot.) I realize that Apple always knows what’s best for you, and has no qualms about telling you so, but geez.